main.py

test_settings = {
	'theme': 'dark', 
	'notifications': 'enabled', 
	'volume': 'high'
}

def add_setting(settings, setting_pair):
	key = setting_pair[0].lower()
	value = setting_pair[1].lower()

	if key in settings:
		return f"Setting '{key}' already exists! Cannot add a new setting with this name."

	settings[key] = value
	return f"Setting '{key}' added with value '{value}' successfully!"

def update_setting(settings, setting_pair):
	key = setting_pair[0].lower()
	value = setting_pair[1].lower()

	if key not in settings:
		return f"Setting '{key}' does not exist! Cannot update a non-existing setting."	

	settings[key] = value
	return f"Setting '{key}' updated to '{value}' successfully!"

def delete_setting(settings, setting_key):
	key = setting_key.lower()

	if key not in settings:
		return "Setting not found!"

	settings.pop(key)
	return f"Setting '{key}' deleted successfully!"

def view_settings(settings):
	if not settings:
		return "No settings available."

	message = f"Current User Settings:\n"
	
	for key, value in settings.items():
		message += f"{key.capitalize()}: {value}\n"

	return message

# =========================
# Example usage / test cases
# =========================

# Add setting
# print(add_setting(test_settings, ('Language', 'English')))
# print(add_setting(test_settings, ('theme', 'light')))  # already exists

# Update setting
# print(update_setting(test_settings, ('volume', 'low')))
# print(update_setting(test_settings, ('brightness', 'high')))  # does not exist

# Delete setting
# print(delete_setting(test_settings, 'notifications'))
# print(delete_setting(test_settings, 'timezone'))  # not found

# View settings
# print(view_settings(test_settings))